Commonly known ozone water purification systems comprise the elements of an ozone gas generating apparatus, a water carrying tube including an ozone contact segment, and in some instances a bubble separating column or chamber. The ozone generating apparatus may comprise a cylindrical chamber through which atmospheric air containing diatomic oxygen is pumped or drawn. Radiation from a lamp capable of emitting intense ultraviolet light having a wavelength of approximately 185 nanometers and 254 nanometers excites the diatomic oxygen within the chamber. As a result of such molecular excitation, a fraction of the diatomic oxygen within the chamber is split, producing free atoms of oxygen. The extremely high chemical reactivity of free oxygen atoms within the chamber causes them to rapidly react with the remaining intact oxygen, forming ozone gas (O3).
Another commonly known method of producing ozone gas within a chamber is to install closely spaced electrodes therein and to, apply a sufficiently high electrical potential between the electrodes to produce electric discharge arcing. Diatomic oxygen molecules in close proximity with such electrical arcing similarly degrade into free oxygen atoms, which quickly react with diatomic oxygen to form ozone gas.
In commonly used configurations of ozone water purification systems utilizing ozone, ozone-rich air emitted from the ozone generator apparatus is introduced into a stream of water in need of purification, such water typically moving through a tube. Where air is forced through the ozone-generating apparatus by, for example, an air compressor, the output of the ozone generator may be introduced into the water-carrying tube by a simple air line interlinking ozone-rich air from the ozone generator to an aperture extending through the wall of the water-carrying tube. In other applications, the air line may terminate at a venturi installed in the water line so that water flowing through the venturi provides motive force to draw the ozone-rich air into the flow of water.
Ozone carrying air either injected into the contaminated water stream or drawn into the stream by a venturi initially exists in the form of air bubbles. In order for the ozone gas to have a purifying effect upon the water, such gas must be dissolved into the water. Such dissolving of the gas into the water necessarily occurs at the spherical surface tension boundaries between the gas and the water. A high solubility differential between common air components and ozone gas causes the ozone within such air bubbles to dissolve more quickly than other gases. An exception to this occurs where an ozone residual exists in water in close proximity to the bubbles. Here, rate of infusion of ozone into the water may be reduced due to the strong negative charge of the ozone molecules. In any case, ozone carrying bubbles must remain immersed in water a sufficient length of time to achieve sufficient diffusion of ozone into the water. In addition, it is well known that where the bubbles are kept small, i.e. prevented from merging into larger bubbles, rate of ozone diffusing into the water is increased. Initially, bubbles from a venturi orifice are small, but soon merge with other bubbles while travelling in the flow of water, which typically just after the venturi becomes laminar.
In some commonly configured ozone water purification systems, the water-carrying tube serves dual functions, both transporting water containing dissolved ozone to its desired destination, and providing an elongated contact distance where air bubbles containing ozone may remain in contact with the water for a sufficient length of time to allow dispersion of the ozone into the water. In order for ozone dispersion to occur within the water-carrying tube, the tube must have a sufficient length, i.e., an ozone contact length. The contact length of the tube may typically be between approximately 1-4 feet or so, and possibly up to 8 feet in length. However, the length may vary depending upon variables such as rate of flow within the tube, size of the tube, turbulence and water temperature. Sharp turns within the tube or turbulence-inducing baffles or screens installed within the bore of the water carrying tube may serve the function of breaking larger ozone-carrying bubbles into smaller bubbles, increasing the overall surface area of the bubbles, and increasing the rate the ozone dissolves into the water. In addition, and as stated, where an ozone residual exists in the water proximate the bubbles, such as where the flow becomes laminar, transfer of ozone from the bubbles is inhibited.
While venturi injectors or mixers such as those used in dissolving ozone into water provide a small bubble size, and as stated, the flow of water just downstream the injector, within 12-15 inches or so, becomes laminar. As such, the bubbles, being entrained in a laminar flow just downstream the injector, become so closely packed together that they merge into larger bubbles. Further, the fluid moving with the bubbles in the laminar flow becomes permeated with ozone, inhibiting further transfer of ozone from the bubbles.
Where water having dissolved ozone gas therein is poured into a body of water such as, for example, a swimming pool, the ozone beneficially reacts with various contaminants. For example, ozone rapidly reacts with metal ions within the water, forming precipitants which may be removed through filtration. Ozone dissolved in water also degenerates or causes lysis of the cell walls of bacteria, viruses, protozoan organisms algae and other microbiota. However, while ozone kills bacteria and viruses almost instantly, protozoa such as those that serve as hosts for bacteria that cause Legionnaires disease require longer exposure to higher concentrations of ozone in order to be killed. Ozone within water also beneficially oxidizes and neutralizes sulfides, nitrates, chloramines, cyanides, detergents, and pesticides. In all such cases, the efficacy of ozone in reacting with such contaminants is enhanced by reducing the physical distance between contaminant organisms or molecules and the molecules of ozone within the water. In a large volume of water, such as a drinking water storage tank, spa, or swimming pool, the concentration of dissolved ozone becomes undesirably low, slowing the rate at which the ozone reacts with contaminants. To prevent such dilution of ozone concentration, it is desirable to first introduce the ozone-carrying water into a reaction chamber having a smaller interior volume which maintains higher concentrations of ozone.
In addition to the foregoing, one problem with indoor pools, spas, hot tubs, jetted bathing facilities and other similar immersion facilities that utilize ozone for sanitization purposes is one of outgassing of the ozone into the area surrounding the facility. Here, strict rules have been enacted that require that outgassing of ozone from such a facility not exceed 0.1 ppm. Thus, it becomes necessary to ensure that little or no ozone is allowed to escape from the water. Further yet, where ozone is generated from air, only a fraction of the approximately 20% oxygen content of the air is converted to ozone. As a result, a relatively large quantity of atmospheric gasses are introduced into the water flow. In some systems, this is undesirable as the gasses produce cavitation of pumps, and where the flow is fast, can erode pipes and other parts of the water-carrying system. As a result, it is necessary in some systems to remove these atmospheric gasses in order to prevent deleterious effects on the system.
In all systems where ozone is used in conjunction with other sanitizers, such as bromine or chlorine, premixing of the sanitizer with ozone or air containing ozone is beneficial. Here, when ozone is premixed with halogens, such as sodium bromide, the bromine is released. With chloramines that are usually present, free chlorine is released. Where bicarbonate of soda is present, hydroxyl radicals are created, which acts as a sanitizer and increases the oxidation potential of the water. Ozone also increases the ground state of halogen sanitizers so that they are more reactive, increasing their sanitizing effects and potential to reduce contaminants.
In accordance with the foregoing, it is one object of the present invention to provide an ozone-based water purification system which incorporates in series an ozone generating apparatus and a mixer for mixing ozone-containing gas and a sanitizer prior to insertion of the mixed compounds into the water.
It is another object of the invention to provide such an ozone-based water purification system wherein turbulence and mixing of the flow of water and bubbles is induced well downstream of the venturi. This keeps bubble size small, and does not allow a buildup of ozone in water proximate the bubbles, allowing more ozone to dissipate into the water. In addition, this mixing and turbulence enhances killing of bacteria and viral organisms.
It is yet another object of the invention to provide a system wherein after the water is sanitized by exposure to at least ozone, any residual ozone remaining in the water is eliminated.
It is still another object of the invention to remove any atmospheric gasses from the flow of water after sterilization.
Other objects and benefits of the present invention will become known to those skilled in the art upon review of the detailed description which follows, and upon review of the appended drawings.